Cooling Modifications

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The first summer weather flying with N66AP was in 2002, and I didn't like the relatively high cylinder head temperatures. On an 85 degree day, cruise CHT's of around 400 were irritating me. While within the green, it is a bit high and limits climb performance. My oil temperatures have always been ok. I did some research and made some modifications in September of 2002. While the warm weather is gone, I believe the engine is now running around 30 to 40 degrees F cooler than it did prior to the modifications, everything else equal. The modifications consisted of trimming 1.25" of the cowl in the exit area, removing the vertical brace, fairing in the nose gear socket, and fairing the motor mount at the exit area. Additionally, I moved the fuel pump drain and the crankcase breather line to the side.

Here are the fairings around the motor mount. The white lines are sunlight. This view is looking directly to the right.

This is the fairing from the firewall over the motor mount. The white skin is the belly.

Here the nosegear socket fairing and firewall/belly fairing can be seen. This view looks right and slightly down.

It is very difficult to really nail down all the variables with regards to cooling to truly assess the affects of a change, but after a summer of flying I would say that the CHT's are running about 20 degrees C, or about 35F cooler, all else equal.